1404 HUMAN ANATOMY. 



The Sweat Glands. The development of these, the most important members 

 of the group of coiled glands, begins during the fifth foetal month as solid epithelial 

 sprouts from the under surface of the epidermis. At first cylindrical in form, 

 these processes soon acquire a club-shaped lower end and for a time resemble 

 developing hair-follicles. The terminal segment of the gland-anlage enlarges in 

 diameter and thus early differentiates the later ampulla. With subsequent increase 

 in length, the characteristic coils soon appear, after which a lumen makes its 

 appearance in the ampullary segment and gradually extends to the surface. 



Practical considerations of the skin find mention in connection with the 

 various regions, to which the reader is referred. 



THE NOSE. 



Although only a small part of the nasal chambers is occupied by the 

 peripheral olfactory organ in man, the greater part forming the beginning of the 

 respiratory tract, comparative anatomy and embryology establish the primary 

 significance of the nasal groove and its derivations as the organ of smell, the 

 relation of the nose to respiration being entirely secondary. The nose, therefore, 

 is appropriately grouped with the organs of special sense, notwithstanding its relation 

 to the proper production of voice and to taste and the role that it plays in varying 

 facial expression. 



The nose consists of two portions, the outer nose (nasus externus) and the inner 

 chamber (cavum nasi), which is divided by the median partition into the right and 

 left nasal fossae 



The outer nose forms the prominent triangular pyramid that projects from the 

 glabella forward and downward, supported by a bony and cartilaginous framework 

 and covered by muscles and integument. Its upper end or root (radix nasi) springs 

 from below the glabella from the frontal bone, with which it usually forms an angle 

 and from which, in consequence, it is separated by a groove. When the latter is 

 wanting and the rounded median ridge, or dorsum, of the nose continues the plane 

 of the forehead, the nose is said to be of the Grecian type. The dorsum ends below 

 in a free angle or point (apex nasi), the upper or bony part of the dorsum, often 

 termed the bridge, in the aquiline type of nose forming a more or less conspicuous 

 angle with the cartilaginous part. 



The sides of the nose (partes laterales nasi) descend from the root with increas- 

 ing obliquity until they reach the broadest part of the nasal pyramid, or base, which 

 is pierced by the openings of the nostrils or anterior nares (nares). Just before 

 meeting the base, each lateral surface expands into the mobile and rounded wing (ala 

 nasi) that forms the outer wall of the nostril and is limited above by a shallow 

 groove, the alar sulcus. Under the influence of the attached muscles, the alae are 

 subject to dilatation, compression, elevation and depression and thereby participate 

 in modifying facial expression. 



In addition to the endless minor variations of form that the outer nose presents, 

 which, apart from individual distinction, have little significance, the relation of its 

 greatest breadth across the alae to its total length, from root to tip, is of sufficient 

 anthropological importance to receive attention in the classification of the races <>f 



i , TM- , . , . , /greatest breadth X ioo\ 



mankind. 1 his relation, the cephalometric nasal index \ 



\ greatest length / 



varies with different races, according to Topinard the index of the white races being 

 below 70 {leptorhines\ that of the yellow and red races between 70 and 85 

 (mesorhines} , and that of the black races above 85 (fi/atyrhincs} . 



THE CARTILAGES OF THE NOSE. 



The cordiform nasal opening ( apcrtura pvriformis ) of the facial skeleton, bounded 

 by the free margins of the nasal and superior maxillary hours, is enclosed and 

 continued to the anterior nares by the nasal cartilages and contiguous fibrous tissue. 

 These cartilages are usually considered as including five chief plates, the unpaired 

 and the paired upper and hncer lateral, and a variable number of smaller 



